Available on TI-99/4A computers. On the top
  
    | Pin | Name | Dir | Description | 
  
    | 1 | RESET | IN | Resets the system (active high) | 
  
    | 2 | GND | - | Signal groud | 
  
    | 3 | D7 | IN/OUT | Data bus, bit 7 (least significant) | 
  
    | 4 | CRUCLK* | OUT | Inversion of TMS9900 CRUCLOCK pin | 
  
    | 5 | D6 | IN/OUT |  | 
  
    | 6 | CRUIN | IN | CRU input to TMS9900 | 
  
    | 7 | D5 | IN/OUT |  | 
  
    | 8 | A15 | OUT | Address bus, bit 15 / also CRU output bit | 
  
    | 9 | D4 | IN/OUT |  | 
  
    | 10 | A13 | OUT |  | 
  
    | 11 | D3 | IN/OUT |  | 
  
    | 12 | A12 | OUT |  | 
  
    | 13 | D2 | IN/OUT |  | 
  
    | 14 | A11 | OUT |  | 
  
    | 15 | D1 | IN/OUT |  | 
  
    | 16 | A10 | OUT |  | 
  
    | 17 | D0 | IN/OUT | Data bus, bit 0 (most significant) | 
  
    | 18 | A9 | OUT |  | 
  
    | 19 | VCC | - | +5 Volts power supply | 
  
    | 20 | A8 | OUT |  | 
  
    | 21 | GS* | OUT | Grom select. Active low is addr in >9800-9FFF | 
  
    | 22 | A7 | OUT |  | 
  
    | 23 | A14 | OUT | Address bus, bit 14. Select mode: low=data / high=addr | 
  
    | 24 | A3 | OUT |  | 
  
    | 25 | DBIN | OUT | Active high = read memory | 
  
    | 26 | A6 | OUT |  | 
  
    | 27 | GRC | OUT | GROM clock: color burst of VDP 9918A | 
  
    | 28 | A5 | OUT |  | 
  
    | 29 | VDD | - | -5 Volts power supply | 
  
    | 30 | A4 | OUT |  | 
  
    | 31 | GR | IN | Active high = GROM ready | 
  
    | 32 | WE* | OUT | Active low = write enable (derived from TMS9900 WE*) | 
  
    | 33 | VSS | - |  | 
  
    | 34 | ROMG* | OUT | Active low if addr in >6000-7FFF | 
  
    | 35 | GND | - | Ground | 
  
    | 36 | GND | - | Ground |